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Патент USA US3074803

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‘United States Patent ()?ice
1
3,874,793
PRQCESS FGR THE PRGDUiITliQN 0F MEDlUM
T0 LGW-CARBON FERRSMANGANESE
August M. Kuhimann, Niagara Falls, N.Y., assignor to
gnigin Carbide Corporation, a corporation of New
or
No Drawing. Filed Sept. 21, 1961, Ser. No. 139,693
7 Claims. (Cl. 75-4335)
3,6743%
Patented Jan. 22, 1963
2
substantially all of the lime necessary for the overall oper
ation in the ?rst process step to provide the prescribed
base-to-acid ratio in the ?nal slag. It should be noted
that this includes sufficient lime to combine with the silica
produced in the silicon reduction step. However, in the
production of low~carbon ferromanganese, particularly
when elemental silicon is used as the reducing agent it is
desirable to add a small portion of the total amount of
lime during the silicon reduction in the ladle to serve as a
This invention relates to a two-step process for the pro 10 heat sink for the excessive quantities of heat evolved by
the exothermic reduction of the manganous slag. If less
lime is used in the ?rst reduction step, the tapping tempera
ture is lowered which results in less sensible heat when
' and medium-carbon ferromanganese alloys is to smelt a
transferred to the ladle. More heat is generated when
charge of manganese ore, lime, and silicon together in an
electric furnace. To carry out the reduction of the man 15 silicoinanganese is added. If there is excessive heat, the
refractories will be eroded. Insu?icient heat produces a
ganese oxides from the tetra- and trivalent state to the ele
buildup of material in the ladle. The amount of lime
mental state requires considerable quantities of costly sili
which may be suitably added in the second reduction is
con which in turn are oxidized to produce silica. The
that amount necessary to combine with the silica produced
presence of silica in the charge results in losses of man
ganese to the slag, the loss being proportional to the con 20 during the silicon reduction and, in addition, up to about
1/s the total lime requirement.
tent of silica in the slag. Furthermore, high silica in the
Any suitable carbonaceous reducing agent may be uti
charge results in high silicon in the product unless the slag
lized
in the ?rst step of the process. Because of the
is ?uxed with lime. This is of particular concern when
versatility and effectiveness of the overall process, coal
it is desired to vmeet a speci?cation calling for less than 1
and the lower grades of coke are quite satisfactory. The
to 2 percent silicon in the ?nal product. In addition, basic
silicon»reducing agent may be elemental silicon or silicon
?uxes must be added to maintain a base-to-acid ratio
alloys such as ferrosilicon. However, silicomanganese is
which, when added to a large quantity of acid slag com
particularly Well suited for the process.
ponent, creates large slag volume in which metal values
In carrying out the second step of the process, the
are easily entrapped.
30 silicon-reducing agent may be added to the melt in the
duction of medium- to low-carbon ferromanganese.
A common method for the manufacture of low-carbon
Two-step reduction practices have been attempted in
order to avoid some of the above-mentioned problems.
However, all of these techniques have required double
furnacing techniques or solid state or gaseous reduction
steps, all of which require additional and specialized
equipment.
It is an object of this invention, therefore, to provide an
improved process for the manufacture of medium- to low
carbon ferromanganese.
Other objects will be apparent from the subsequent dis
closure and appended claims.
The process which satis?es the objects of the present
invention comprises smelting manganese ore with at least
su?'lcient carbonaceous reducing agent to provide a melt
containing substantially all of the manganese values in the
manganous state without the substantial reduction of the
manganese values to elemental manganese, transferring
the melt to a ladle, and reducing the manganese values to
elemental manganese with a silicon-reducing agent.
In the ?rst step of the process it may be desirable to use
more than the stoichiometric amount of carbonaceous
ladle in the molten or solid state or may be part molten
and par-t solid. The various reactants and additives may
be introduced into the ladle simultaneously or in sequence.
The mixture of reactants may be poured from one ladle
to another to promote complete reaction. It has been
found desirable to feed a stream of dry granular silico
manganese con?uently with the ‘stream of melt into the
ladle. This eliminates the need for melting the reducing
agent while simultaneously providing a heat sink for a
portion of the excess heat from the exothermic reaction.
The process of the present invention may be varied to
produce either high- or low-silicon products. Those vari
ations will be discussed separately below.
Low-silicon ferromanganese can be produced directly
from the manganous oxide-containing melt by addition
thereto of the stoichiometric amount of silicon-reducing
agent. If it is desired to produce a throw-away slag, sufQ
?cient lime should be incorporated to provide a ?nal
slag containing from about 6 to 12 weight percent MnO
and having a base-to-acid ratio over 1.8.
The process is more effectively carried out if the slag
reducing agent for the reduction of all the manganese to
produced
simultaneously with the low-silicon ferromanga
the manganous state. Thus, any excess of iron oxide may
nese is maintained high in manganese values. This, how
be reduced to the elemental metal. When the manganese—
ever, requires recovery of the manganese value from the
bearing slag is poured into the ladle for the second reduc
tion step, the reduced iron may be left behind thereby 55 slag if the favorable economics of the process are to be
maintained. Fortunately, the slag is readily treated for
e?ectievly lowering the iron content of the ?nal manganese
this purpose.
.
product. It should be noted, however, that the excess of
If silicomanganese is ‘a desired product, the ?rst silicon
carbonaceous reducing agent should not be such as to
reduction can’ be conducted to produce a non-disintegrat
cause formation of more than minor amounts of elemental
60 ing slag (about 20 to 25 percent MnO and higher). This
manganese.
The melt produced in the ?rst step should have a molar
base-to~acid ratio of at least 1.6, i.e., the ratio
MnO-l-CaO-l-MgO-l-BaO
slag can then be carbon-reduced in a furnace to the de-
sired silicomanganese.
‘ If the slag produced from the ?rst silicon reduction con
tains in excess of 30 percent MnO (normally about 35
65 percent and higher), it may be reacted with ferromanga
,
SiOz
nese silicon or ferrosilicon to produce high-silicon, low
should be 1.6 or higher. For speci?c variations in the
carbon (0.1 percent maximum) ferromanganese and a
process and in the products produced, higher ratios may
slag. The slag may be utilized for silicomanganese pro
be desirable.
The process may be operated as a lime-free process or 70 duction as before.
Alternatively, the slag may be reduced with ferro
lime may be added to produce a desired slag of particular
manganesensilicon followed by molten resiliconization
composition. in most operations it is desirable to add
3,074,793
3
4
with silicomanganese to produce 0.75 percent carbon
ferromanganese containing 5 to 7 percent silicon.
Finally, the high-manganous oxide slag from the ?rst
‘silicon ‘reduction may be reacted with regular silicomanga
complete reaction. The bulk of the slag formed was
poured 01f, and the balance, including metal and remain
ing slag, was cast into steel billet chills. The resulting
alloy analyzed 89.6 percent manganese, 0.05 percent sili
nose to produce a novel product, high manganese, sili C11 con, 0.04 percent carbon, and the balance iron. The slag
comanganese having a manganese content of at least 75
contained 26.47 percent calcium oxide, 26.37 percent sili
percent, a weight ratio of manganese to silicon of at
con dioxide, 27.94 percent manganese, and 0.18 percent
least 5, and a maximum carbon content of 1.5 percent.
iron.
This product is a superior deoxidizer for steels; [the high
Example II
manganese-to-silicon ratio results in a high MnO-to
A
charge
consisting
essentially of 15,000 pounds of
SiO2 ratio after deoxidation which, as has been shown
Belgian Congo ore, 1000 pounds of low ash coal, and
by C. H. Herty, provides optimum conditions of melting
4200 pounds of lime was fused in a tilting submerged are
point, Viscosity, fluidity, and density, thereby increasing
electric furnace. After the charge was completely fused,
the melt analyzed 1.9 percent available oxygen. About
17,000 pounds of the melt were tapped into a ladle while
con?uently 7700 pounds of solid granular 1/1 inch by
the case of separation of the deoxidized steel from the
deoxidation products to give a cleaner deoxidized steel.
Silicoman‘ganese having such a manganese-to-silicon ratio
is not normally obtainable by standard processes.
down mixture consisting of 75 percent silicomanga'nese'
If it is desired to produce high-silicon ferromanganese
directly from the carbon-reduced manganous oxide melt,
(19.6 percent silicon, 1.3 percent carbon, 67.9 percent
a silicon-reducing agent is added to the melt in the stoi 20 manganese, balance iron) and 25 percent cobbings (59.7
percent manganese, 2.2 percent carbon, 18.6 percent sili—'v
chiometric amount to produce the desired product and
con, balance iron) were added. At the conclusion of
a slag having a base-to~acid ratio of at least about 1.8.
the tap, the ladle contents were poured into another ladle
When demand for high-silicon ferromanganese is high,
to complete the reaction. The bulk of the slag was
all of the melt can be so converted. When there is also
a demand for low-silicon ferromanganese, only a portion 25 poured 01f, and the balance was cast into steel billet
chills. The resulting alloy analyzed 81.6 percent mangai
of the melt is converted to high-silicon ferromanganese;
nese, 1.0 percent silicon, 1.3 percent carbon, and the
a portion of the latter product is then employed to reduce
balance iron. The slag contained 26.69 percent calcium
the balance of the melt to low-silicon ferromanganese.
oxide, 25.91 percent silicon dioxide, 0.15 percent iron,
Thus, by apportioning the amount of melt to be con
verted to high-silicon ferromanganese and the ‘amount of 30 and 27.84 percent manganese.
this product to be recycled for production of the low
Example III
silicon product, two saleable products can be produced
‘In carrying out, a process, in accordance with the i114
in relative proportions which are easily varied to match
vention for, the production of low-silicon, medium-carbon
demand.
From the foregoing discussion, it has been shown that 35 ferromanganese, a charge consisting of 1000 parts of
high-grade manganese ore, 83 parts of coal, and 217 parts
the subject process of partial carbon-reduction of ore in
of lime was fused in a submerged are electric furnace.
a furnace followed by silicon-reduction in a ladle permits
production of a number of manganese-silicon alloys of
low-to-medium carbon content; only a single furnace is
After bringing the charge to complete fusion, at which
time the melt analyzed, 45.90 percent manganese and 0.39
required, and the versatile process permits easy change 40 percent “available oxygen,” it was tapped into a ladle.
while at the same time and con?uently, _a mix of solid
from one product to another depending on market de
mands. The advantages will be further seen from the
granular silicomanganese and silicon so proportioned tov
following examples.
give an average silicon content of 22 percent was fed.
The resulting alloy analyzed 82.02 percent manganese,
,
Typical ore compositions for the examples are shown
inTable I.
‘
45
TABLE I
0.39 percent silicon, and’ 0.73 percent carbon. ,The‘resulte
ing slag analy'ze'd 29.51 percentmanganese, 23.52 percent‘
SiO'Z, 26.92 percent CaO,, and 2.80 percent MgO.
Component
7,
One of the important'features of_ the present invention
is the ability to utilize the slag'from the second stage of
Belgian Congo South African
Ore,’ Percent Ore, Percent
the process as ‘a source of manganese for the production
51. 3'
,1. 9
13.6
3. 6
5. 2
0. 1
55. 0
1. 4
13.0
3. 5
1. 9
0.02
In the table, available 02 indicates the amount of oxy
gen which must be reacted with‘ the carbonaceous reduc
ing agent in order to‘ reduce all of the manganese values
to the manganous state.
50 of a variety of alloys low in carbon.
This slag is a suit
able starting material for the production of a high-silicon‘
ferromanganese alloy by treating it with silicon-reducing
agent as before.
55
Example IV
. In producing high-silicon ,ferromanganese from slag
from low-silicon, low-carbon alloy production, 30,200'
pounds of slag analyzing 24.73 percent oxidic manganese,
27.87 percent SiO-Z', 28.32 percent‘ CaO, produced in ac—
60 cordance with the method of Example III, were treated
Example I
with 3,700 pounds ofmolten ferromanganese silicon ana
To illustrate the process of the present'invention for
lyzing 29.80 percent silicon, 0.062 percent carbon, to
producing. low-silicon, low-carbon‘ ferromanganese, 7500'
produce 5,495 pounds of an alloy analyzing 81.67 per
pounds of Belgian Congo ore, 7500 pounds of South Afri
cent manganese, 13.55 percent silicon, 0.050 percent car
can ore, 900 pounds of low ash coal, and 4100 pounds of
bon, and a slag‘ analyzing 20.08 manganese, 29.11 CaO,
lime were fused in a tilting submerged are electric fur
nace. When the charge was brought to complete fusion,
the melt analyzed 3 percent available oxygen. At this
point 17,500 pounds of the melt were tapped into a ladle
while con?uently 5400 pounds of 14 inch by down sili
29.85 SiOg.
_,
I
_
Example V
In producing high-silicon ferromanganese from slag
from low-silicon, medium-carbon alloy production,
comanganese analyzing 29.5 percent silicon, 0.09 percent 70 20,100 pounds of slag, analyzing 29.88 percent manga
nese, 25.93 percent SiO2, 20.70 percent CaO, produced
carbon, 64.4 percent manganese, 0.04 percent phosphorus,
in accordance with’the method of Example III, were
and the balance iron were added. At the conclusion of
treated with 3000 pounds of molten ferromanganese sili
the .tap, the ladle contents were repoured into a second
conianalyzing
36 percentsilicon, 59.77 percent manga
ladle‘ for the purpose of bringing about more rapid and 75 nese, 0.080 percent
carbon to produce 4,310 pounds of
spams
6
6
‘an alloy analyzing ‘82.56 manganese, 13.64 silicon, 0.080
into another ladle for the purpose of bringing about a
carbon and a slag ahalyzin’g 211.08 manganese, 28.13 CaO,
28.36 SiOg.
thus formed is poured off to be routed to a furnace for
producing silicomanganese to be used in the above reac—
more rapid and complete reaction. The bulk of the slag
Example VI
To illustrate slag reduction with solid reductant, 20,350
‘pounds of slag produced in accordance with Example III
from low-silicon, medium-carbon alloy production, ana
tion step. The resulting alloy analyzed about 80 percent
manganese, 20 percent silicon, and 0.1 percent carbon;
2100 pounds are reacted with 8750 pounds more of the
melt in a ladle as above.
The slag is poured 015.‘ and
lyzing 30.55 percent manganese, 24.7 percent SiOZ, 20.8
used to make more silicomanganese as before, while the
percentCaO, were treated with 2,900 pounds of solid 10 resulting alloy analyzing 80 percent manganese, 1.5 per
cent silicon, and 1.25 percent carbon is cast into steel
ferromanganese silicon, analyzing 33.26 silicon, 62.16
manganese, 0.103 carbon, to produce 3,790 pounds of
billet chills.
Example XI
manganese-silicon alloy, analyzing 14.46 percent silicon,
81.89 percent manganese, 0.072 percent carbon and a slag
‘To produce the novel high manganese-to-silicon ratio,
containing 24.62 manganese.
15 silicomanganese described previously, standard molten
silicomanganese (typically 66.5 percent manganese, 19.5
Example VII
percent silicon, 1.5 percent carbon, and a maximum of 0.05
Following the procedure of Examples III and IV, 107 0'
percent phosphorus) are reacted with high-manganese slag
pounds of molten slag having 31.09 percent manganese
(typically about 30—35 percent manganese) to produce an
were treated with 220 pounds of ferromanganese silicon.
alloy analyzing typically about 79 percent manganese, 15
The resulting alloy weighing 240 pounds analyzed 79.55
percent silicon, 1.25 percent carbon, and a maximum of
percent manganese, 16.22 percent silicon, and 0.08 per-.
0.05 percent phosphorus and a slag containing about 25
cent carbon.
percent MnO.
Example VIII
Advantages of the new process include better recovery
In practicing the invention for the production of a 10 25 of manganese and lower carbon content of the alloy for
percent silicon ferromanganese alloy, a charge consisting
the same carbon content of silicomanganese, due to im
essentially of high-grade ore and coal was fused in a sub
proved recovery of manganese from ore and a suitable
merged are electric furnace. The composition of the
usage of silicomangane‘se.
Another factor contributing to a lower carbon product
charge was as follows: 59.84 percent total manganese,
2.70 percent as MnO2, 5.90 percent SiO2, 0.47 percent 30 is the fact that all reduction is carried out in a ladle away
from possible carbon contamination from electrodes in
CaO, and 1.19 percent MgO.
After bringing the charge to complete fusion, 750
an electric furnace.
A still further advantage lies in the fact that the slag
pounds of the melt were tapped into a ladle. To the ladle
resulting from the ladle reaction is sut?ciently rich in
was then added molten ferromanganese silicon (analyzing
31.04 percent silicon) until 400 pounds were added. The 35 manganese to serve as an intermediate in subsequent
resulting alloy amounting to about 516 pounds analyzed
metallurgical reactions.
The product alloy is sounder (less porous) than conven
81.75 percent manganese and 10.03 percent silicon. The
slag which resulted amounted to approximately 705
pounds and contained about 38.37 percent manganese.
Example IX
Following procedures and employing the equipment of
tional products.
40
This application is a continuation-in-part of copending
application Serial Number 77,825 ?led December 23,
1960.
What is claimed is:
‘1. A process for the production of medium-to-low
Example VIII, 880 pounds of melt were reacted with 400
carbon ferromanganese which comprises smelting man
pounds of ferromanganese silicon to yield 523 pounds
of alloy and 760 pounds of slag. The composition of 45 ganese ore with at least su?icient carbonaceous reducing
agent to provide a melt containing substantially all of
the reactants and products are set forth in the table
the manganese values in the manganous state without sub
below.
stantial reduction of the manganese values to elemental
manganese and having a molar based-to-acid ratio of at
Melt
FeMn-Si
Alloy
Slag
least 1.6; transferring the melt to a ladle; and adding to
50
said melt sufficient of a silicon-reducing agent to reduce
Total, Mn 59.36
Mn, 64.5
Mn, 82.63
Mn, 38.67
manganese value to produce a ferromanganese alloy and
as MnOs, 6.96
',
Si, 8.78
a slag having a base-to-acid ratio of at least about 1.8.
810;, 4.98
C, 0.1 max.
030, 0.98
2. A process in accordance with claim 1 wherein suf
MgO, 0.72
?cient lime is introduced during the carbon and silicon
55
reduction steps to produce a throw-away slag containing
from about 6 to 12 weight percent MnO.
Example X
3. A process in accordance with claim 1 for the simul
In carrying out a process in accordance with the in
taneous production of high-silicon and low-silicon ferro
vention for the production of low-silicon ferromanganese,
a charge, consisting essentially of high-grade manganese 60 manganese of low-to-medium carbon content wherein the
ladle silicon reduction is conducted on only a portion
ore of the composition of Table I, coal, and lime, is fused
of the melt to produce high-silicon ferromanganese, and
in a tilting, submerged arc electric furnace, the composi
a quantity of the high-silicon ferromanganese so produced
tion of the charge being as follows:
is reacted with the balance of said melt in a ladle to pro
Lb.
duce low-silicon ferromanganese.
4. A process in accordance with claim 1 wherein the
silicon reduction step is conducted to produce a high
manganese slag containing in excess of 30 percent M110
and reacting said slag with a silicon reductant to produce
a silicon-containing manganese alloy.
70
5. A process in accordance With claim 4 wherein said
high-manganese slag is reacted with a reductant selected
from the group consisting of ferromanganese silicon and
ferrosilicon to produce a high-silicon, low-carbon ferro
75 manganese and a second slag.
Belgian Congo Mn ore ____________________ __ 15,000 65
Low-ash coal ____________________________ __
Lime _______ _-
._
900
4,100
After bringing the charge to complete fusion, the melt
analyzing 3 percent “available oxygen,” 8750 pounds of
the melt are tapped into a ladle, while at the same time
and con?uently, solid granular 1%; by D silicomanganese
of the composition 29.5 percent silicon, 64.6 percent man
ganese, 0.09 percent carbon, and 0.04 percent phosphorus
is fed until 2700 pounds are added. At the conclusion
of the tap, the ladle contents are immediately repoured
7
2s
_6. A process in accordance with claim 4 wherein said
high-manganese slag is reduced with ferromanganese sili,con, and the alloy so produced is resiliconized with silicomanganese to produce 0.75 percent carbon ferrornan
ganese containing 5 to 7 percent silicon,
'
a manganese content of at least 75 percent, a weight
ratio of manganese-'torsilicon of at least 5, and a maxi
mum carbon content of 1.5 percent.
5
References Cited in the ?le of this patent
7. A process in accordance with claim 4 wherein said "
high-manganese slag is reacted with regular silicomanganese to produce high-manganese silicomanganese having
UNITED STATES PATENTS
V
1,763,112
Brellan -------------- -_ June 24, 1930
3,043,681
Ud'y et a1 _____ __' ______ __ July 10, 1962
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